Welcome to G1 Insight ownership! These are old cars with aging parts and batteries, and even the replacement batteries are starting to age, so what you're experiencing are pretty normal symptoms these days, although not technically normal behavior.
That's why I had Daox fabricate my three-button shifter, so Insight owners can have more control of the IMA system right at our fingertips. I usually have the IMA assist off (clutch button) while I'm driving. I click the clutch switch back on and then push the brake regen button when I have to slow down. This recharges the IMA at almost full bars while slowing, and it makes the brake lights come on. Using these two buttons on my shift knob keeps my IMA battery pretty much fully charged at all times. I haven't bothered to install the kill switch on my new Insight yet.
Another useful mod I have on my car is a quick disconnect for the 12V,which I use every morning to keep my IMA system from all the force-charges and recals. I open it for about five seconds, and my car will go through a quick recal when I start it up, which lasts about a mile when I start out every morning. Then I never have to worry about getting on the highway and having to drive 20 miles while the car is force-charging
